The present invention generally relates to printer apparatus and methods and more particularly relates to a printer and receiver supply cassette therefor, and method of assembling same.
Thermal printers form a color print by successively printing with a dye donor onto individual sheets of a dye receiver (i.e., paper or transparency). The print head of such a thermal printer commonly includes a print line of thermal resistive elements that can be individually heated in order to transfer dye from the donor to the receiver. Such print heads can take any of several forms including resistive element, resistive ribbon and laser print heads.
More specifically, a typical color thermal printer includes the previously mentioned print head and a platen. A picker mechanism "picks" individual sheets of the receiver from a stack of cut sheets of the receiver and feeds the individual sheets into a nip area defined between the print head and platen. The print head is then lowered, so that the donor and receiver sheet are sandwiched between the print head and platen. An image is printed on the sheet by selectively heating the elements of the print head in order to transfer a first dye to the receiver sheet. The receiver sheet is then repositioned to receive a second color of the image, and the donor is positioned to provide a second dye color. These steps are repeated until all colors of the image are printed and the completed print is ejected from the printer.
Moreover, a receiver supply tray loaded with the stack of cut receiver sheets is removably inserted into the printer for providing a supply of sheets of a predetermined size to be printed by the print head. A typical supply tray includes an adjustable backstop for restraining longitudinal movement of the stack of cut sheets. The backstop is adjustable for accommodating various sizes of receiver sheets. However, this backstop typically includes a plurality of individual parts that must themselves be manufactured and thereafter precisely assembled during manufacture of the supply tray. Such, manufacture and assembly of these parts complicates manufacture of the supply tray and therefore increases manufacturing costs. Therefore, a problem in the art is increased costs due to manufacture and assembly of supply trays having a plurality of moving parts.
Receiver supply trays having backstops are known. A feed cassette for use with copying machines is disclosed in U.S. Pat. No. 4,032,136 titled "Feed Cassette" issued Jun. 28, 1977 in the name of Shiro Komaba, et al. This patent discloses a slidable limit plate for positioning copy mediums in accordance with the sizes thereof. The limit plate is attached to an inner plate and is locked by a stop plate that is received in a corresponding rectangular opening formed in the inner plate. Although the Komaba, et al. patent discloses a limit plate for positioning copy mediums, the Komada et al. device nonetheless includes an assemblage of individual parts that apparently must be separately manufactured and then precisely assembled. Therefore, the Komada et al. device does not appear to address the problem of increased costs due to assembling supply trays having a plurality of individual parts.
In addition, prior art supply trays commonly include "click type" detents in which the backstop detent is chamfered and is overpowered by the operator when the operator needs to move the backstop to a different position. Click type detents must try to strike a balance between force necessary to retain the receiver and force that the operator is comfortable in applying to move the backstop. Click type detents are subject to reduction of retaining force by wear.
Therefore, there has been a long-felt need to provide a suitable printer and receiver supply cassette therefor, and method of assembling same which overcome the above-recited problems associated with the prior art.